This is a large active source experiment to seismically image the magma plumbing system of an arc volcano throughout the crust and into the upper mantle. We will record the RV Langseth 7,000 cu in air gun array on 91 SP OBS and 26 land stations with an aperture of up to 100 km for 3D tomographic imaging and with sufficiently high density for full waveforminversion.